<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
</head>
<title>
    Document
</title>
<style>
    * {
        padding: 0;
        margin: 0;
    }
    
    .btys {
        width: 100vw;
        height: 10vh;
        background: #369;
        color: #fff;
        text-align: center;
        line-height: 10vh;
        font-size: 18pt;
    }
    
    .outer {
        width: 300px;
        height: 300px;
    }
    
    .inner-header {
        width: 300px;
        height: 50px;
        background: #369;
    }
</style>

<body>
    <div class="outer">
        <div class="inner-header"></div>
        <div class="inner-body"></div>

    </div>
</body>

</html>